JP4398251B2 - Food cooking basket for pressure pan, pressure pan for receiving cooking basket, and method for making cooking basket by swaging - Google Patents

Abstract

The method involves perforating a rigid stainless steel sheet on all its surface and cutting the sheet to obtain a blank at a final shape of a circular basket. The blank is stamped in its central part, where the stamping is made in a manner that the junction between base (2) and lateral walls (3) of the basket presents a regular curve. Edges of the blank are stamped to obtain a basket (1), where the edges are stamped till upper peripheral edge (6) of the base is curved towards exterior.

Description

  The present invention relates to the general technical field of appliances for performing pressure cooking, such as a pressure pan, and in particular, for cooking food, in such appliances, at a certain height in the container. It relates to a food-cooking basket designed to be advantageously arranged there.

  The invention also relates to a method of making a food pan-cooking basket for a pressure pan, said basket being made from a metal sheet and obtained by stamping.

  The present invention relates to a food-cooking basket for pressure cooking with a pressure pan, the basket being formed by a sheet of rigid material defining the bottom and side walls of the basket. The sheet includes a plurality of through holes, and the plurality of through holes allow the steam in the sealed box of the pressure pan to pass therethrough and pass through foods, in particular, a plurality of vegetables contained in the basket. Is acceptable.

  The present invention also relates to a pressure pan having a container and a cover for receiving a cooking basket. The container includes support means for supporting the basket within the container. The support means is arranged in or on the wall to hold the cooking basket in a predetermined position at a distance from the bottom of the container for performing a steam cooking cycle.

  The present invention also relates to a method for making a food pan-cooking basket for a pressure pan by stamping a metal sheet.

  In order to allow users of pressure pans to cook by anything other than immersing food in the liquid contained in the cooking container, it is necessary to prepare a cooking basket that is contained in the container and contains the food At a certain predetermined height in or on the wall so as to allow the basket to be supported at a predetermined height above the cooking liquid. There is also a need for a means for supporting the cooking basket placed on. It is also necessary to provide a certain number of through-holes in the basket so that the steam can circulate not only in the pressure pan, but also between the foods, thereby optimizing heat exchange.

  Such systems are well known and utilize baskets of various shapes and volumes, generally metal baskets. The basket support means is composed of a detachable support formed from a steel wire disposed at the bottom of the container, for example, when the user wishes to perform steam cooking. There are also support means formed by a plurality of pieces (rivets) attached to the wall of the container and support means formed by locally deforming the wall of the container. These deformations support the basket at a predetermined height above the bottom of the container.

  Currently known metal baskets can be classified into two main types.

  The first type is made up of “net” baskets that are obtained using interlaced or interlaced or meshed steel wires and have a reinforcing structure that provides mechanical strength. Such baskets are generally satisfactory. However, it is very difficult to clean, especially due to the disadvantages associated with the difficulty of containing food, caused by the large mesh size, and the mesh especially difficult to ensure that food waste is removed There are drawbacks associated with difficult things. Furthermore, such baskets are relatively fragile and have a short life.

  A well-known second type of basket is obtained by stamping and includes a series of through holes formed either through the bottom of the basket or through both the bottom and side walls. It is formed by a metal basket. Such baskets are generally satisfying and can be easily cleaned. However, the ability to ensure good heat exchange with food is very variable and difficult to control.

  It is also known that a balanced diet requires regular intake of vitamins, especially vitamin C, from the main sources of fruits and vegetables. Research conducted on this issue not only shows that the consumption of fruits and vegetables by the general public has been inadequate over the past few years, but also the general trend is This shows that the consumption is in a relatively decreasing direction. One of several factors that may explain or clarify the low level of consumption and general trends is that a potential consumer or potential consumer may use fruits and vegetables in use. A set of constraints that tend to limit the consumption of food, especially the need to obtain food frequently, the need to clean and peel the food, and ultimately to vegetables To face the need to perform cooking operations. This limitation, which is negatively or negatively recognized, is understood to be a limitation related to the time required for cooking.

  Therefore, there is generally a need to improve normal dietary conditions, or at least prevent it from getting worse, and a solution that makes it possible to shorten the time required to cook food, especially vegetables. The investigation for was led.

  It is also known that vitamins are very sensitive to cooking conditions and can be destroyed, leached or dissolved, decomposed or degraded completely or partially during cooking. In general, among the various vitamins, vitamin C is most fragile, even if fruits and vegetables contribute to about 85% of the dietary intake of vitamin C. Therefore, it is extremely important to maintain the amount of vitamin C in the vegetable after it has been cooked, especially after pressure cooking.

  Among the known phenomena related to fragility in cooking of vitamin C contained in vegetables, vitamin C is soluble in water when it is in the form of folate which is sensitive to leaching or dissolving by cooking water. Can be mentioned. Furthermore, vitamin C is sensitive to temperature and is destroyed in proportion to the time and temperature applied during cooking.

  Finally, vitamin C is sensitive to oxidation and is therefore degraded or degraded in response to increased contact with air.

  Thus, there is also a general problem of preserving various vitamins, especially vitamin C, while cooking vegetables in a pressurized cooker such as a pressure pan.

  Accordingly, the object given to the present invention is to provide a novel food-cooking basket for use in pressure cooking in a pressure pan, which basket is required for cooking food. It makes it possible to reduce time, while preserving the multiple vitamins present in foods, especially vegetables.

  Another object of the present invention is to propose a new food-cooking basket that can optimize the circulation of steam in the pressure box closed box, while being easy to manufacture in an industrial manner. is there.

  Another object of the present invention is to provide a novel food-cooking basket that is easily cleaned.

  Another object of the present invention is to propose a novel cooking basket that does not impede the operation of the pressure pan safety member in which the basket is mounted.

  Another object of the present invention is to provide a novel food-cooking basket that is particularly robust and easy to manufacture while being easy to handle and suitable for positioning at will. To do.

  Another object of the present invention is to propose a novel cooking basket that is easy to handle without causing the risk of burns.

  Another object of the present invention is also to propose a novel pressure pan that allows different types of food to be cooked in different ways under pressure without disturbing the normal and safe operation of the pressure pan. To do.

  Another object of the present invention is to propose a new method for producing a food-cooking basket which can be obtained in a simple and repetitive manner by stamping.

  Another object of the invention is to propose a new production method which is particularly simple and effective to carry out.

  The object given to the present invention is achieved by a food-cooking basket for pressure cooking in a pressure pan, said basket being formed from a sheet of rigid material defining the bottom and side walls of the basket, said sheet comprising: A basket provided with a plurality of through-holes, wherein the plurality of through-holes are provided to penetrate at least the side wall and represent at least 30% of the total area of the sheet.

  The object given to the present invention is also achieved by a pressure pan for receiving the basket of the present invention, the pressure pan comprising a container and a cover, said container being arranged in or on the wall within the container. A pressure pan with support means for supporting the basket, wherein the container is at a plurality of different heights in order to allow the at least two cooking baskets to be placed one on top of the other in the container. It is characterized by having at least two rows of support means arranged.

The object of the present invention is also achieved by a method of making a food pan-cooking basket for pressure pans by stamping a metal sheet, the method comprising the following sequential steps:
a) perforating a metal sheet;
b) cutting the sheet to obtain a blank having the final shape of the basket;
c) stamping the center of the blank, and
d) trimming the edges to obtain a basket;
I have a,
The sheet is characterized in that a plurality of through holes are perforated so as to represent at least 30% of the total area of the sheet .

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will be explained in more detail by reading the following description and from the accompanying drawings given as non-limiting examples.

here,
FIG. 1 is a perspective view of a cooking basket of the present invention,
FIG. 2 is a plan view of the same cooking basket as the present invention and the basket shown in FIG.
FIG. 3 is a sectional view showing details of the structure of the cooking basket of the present invention,
FIG. 4 is a cross-sectional view showing the cooking basket at a high position inside the pressure pan,
FIG. 4A is a cross-sectional view showing a pressure pan of the present invention comprising two cooking baskets according to the present invention in a stacked arrangement or configuration;
FIG. 5 shows various successive stamping steps that result in the fabrication of the cooking basket of the present invention,
FIG. 6 shows the uniformity of the temperature rise of the food within the cooking basket of the present invention, and
FIG. 7 is a graph equivalent to the graph of FIG. 6 and illustrates the non-uniformity in temperature rise of food contained in a prior art cooking basket.

Best Method of Carrying Out the Invention The food-cooking basket of the present invention is designed to be used and placed in a pressure-pan type food-cooking utensil. Regardless of whether the pressure pan is a clamp type, a claw type, a plug-in type or a manhole type, it is not limited to this list.

  In the following description, the cooking basket of the present invention is advantageously formed in the shape of a circular basket, but is not limited to this shape, and the cooking basket of the present invention does not exceed the scope of the present invention. The shape may be other than a circle, such as a rectangular shape or a square shape.

  The food-cooking basket 1 shown in FIGS. 1 to 5 is used for pressure cooking in a pressure pan, and is constituted by a sheet made of a rigid material that defines the bottom 2 and the side wall 3 of the basket 1, The sheet is provided with a plurality of through holes 4.

  In the meaning of the present invention, the rigid material can withstand use in a pressure pan in contact with food, permanently and continuously, and can be subjected to continuous and repeated cleaning operations; And can be based on any material capable of undergoing an operation to raise the temperature and pressure of the pan.

  Advantageously, the rigid sheet material is made of metal, preferably stainless steel, but nevertheless other types of materials, in particular plastic materials, without exceeding the general scope of the invention It is understood that can be foreseen.

  According to an important feature of the present invention, the plurality of through holes 4 penetrate at least the side walls 3 so as to represent at least 30% of the total area of the sheets constituting the basket and forming the area of the entire basket. Are arranged.

  Below this ratio, which indicates the ratio between the surface area of the sheet forming the container body and the plurality of through holes 4, it has been found that it is difficult to industrially manufacture the basket. In particular, the effects relating to reducing cooking time and retaining the vitamins of the food contained in the basket 1 are not good and beneficial.

  Advantageously, the plurality of through holes 4 in the side wall 3 start from the bottom of the side wall 3 adjacent to the bottom 2 and are substantially regular or uniform so as to substantially occupy the entire circumference of the side wall to a defined height. In this manner, it is formed and distributed.

  Reduced vitamin retention effect and cooking time when the plurality of through holes 4 are located in the lower portion of the basket 1 to a defined height that substantially matches the depth of food present in the cooking basket 1 Has been found to be even more pronounced.

  Preferably, the plurality of through holes 4 represent at least 35%, preferably 35% to 58% of the total area of the sheet.

  In a particularly advantageous manner, as shown in FIGS. 1 to 5, the plurality of through holes 4 are distributed substantially uniformly throughout and through the bottom 2 and the side walls 3. It has been found that the best results are obtained with a basket with a plurality of through holes 4 up to a considerable height of the bottom 2 and side walls 3 of the basket.

  As shown in FIGS. 1-5, in a preferred variant, the plurality of through holes 4 in the side wall 3 have a top edge 6 on the side wall 3 so as to obtain a cooking basket whose entire surface area is uniformly perforated. It is formed completely.

  As shown in the figure, the plurality of through holes 4 are advantageously substantially circular and have a diameter that is at least 3 millimeters (mm), more preferably in the range of 3 mm to 5 mm. Still, the plurality of through holes 4 can be other shapes and larger sizes without exceeding the scope of the present invention.

  When the through hole 4 has a circular shape, the plurality of through holes are spaced apart at regular intervals. When the thickness of the sheet made of the rigid material is in the range of, for example, 0.4 mm to 0.8 mm, and more preferably about 0.5 mm or about 0.4 mm, the thickness is, for example, 5 mm to 8 mm. They are arranged at regular or uniform pitch.

  As shown in the figure, the plurality of through holes 4 may be arranged in a regular line, or may be T-, U-, M-, or Z, depending on the geometrical arrangement of the through holes relative to each other. It can be arranged in a favorite arrangement known as shape.

  As shown in FIG. 3, the joint between the bottom 2 and the side wall 3 is advantageously formed to exhibit a constant curvature, for example, has a radius of curvature R greater than or equal to H / 2. Here, H is the height of the basket 1 (see FIG. 3). Maintaining the radius of curvature has been found to help reduce internal turbulence due to cooking steam. Otherwise, the cooking steam may tend to interfere with the correct lifting operation of the pressure pan safety device, in particular the safety lock valve (or safety lock valves).

  Advantageously, the basket 1 of the present invention has a circular cross section with a diameter D and a height H substantially equal to 1/3 D.

  As shown in FIGS. 1-5, the side walls 3 are terminated at their apexes by a curved edge 6, which is constant over the entire circumference, radially outward from the basket in question and its axis of symmetry. It extends beyond a certain width. This feature allows the cooking utensil to be placed in a pressure pan without any specific indexing. Furthermore, due to the presence of a continuous curvilinear edge 6 for attachment to the inner wall of the pressure pan container (ignoring the clearance required to allow the basket to be inserted), steam passes through the basket. Thus passing through the food, which optimizes heat transfer.

  The curved edge 6 is advantageously provided with a peripheral ring 7 made of metal, for example. The peripheral ring is mounted on the edge and bent around the edge in order to increase the rigidity of the basket and improve the finish of the basket.

  1-3, the basket of the present invention has a handle 8, which is between the basket-supporting position shown in FIG. 1 and at least one resting position shown in FIG. It is attached to rotate. In the rest position, the handle rests or rests on the top edge 6 of the basket and lies substantially on the periphery of the edge. In this shape, the handle 8 has a substantially semicircular shape.

  Advantageously, according to the present invention, the handle 8 includes a grip portion 9 substantially at its center. The grip part is based on silicone and is retracted inward from the rest of the handle so that the grip part does not rest on the edge 6.

  In the preferred variant shown in FIG. 2, the grip portion 9 is curved and defines a concave portion 9A facing towards the outside of the basket and a convex portion 9B facing towards the inside of the basket. A curved part is formed. This feature makes it very easy to grab the handle without burning the fingers.

  As shown in FIGS. 4 and 4A, the cooking basket 1 is placed in a pressure pan 10 with a cover (not shown) for performing pressure cooking.

  The pressure pan of the present invention has a container 10, which has support means 11 for supporting the basket 1 in the container. The support means 11 is formed in a radial direction on or from the wall 10A of the container. These plurality of support means 11 are well known to those skilled in the art and are obtained, for example, by pressing or deforming the walls as disclosed in patent FR-2 783 685 in the name of the applicant. Or a similar indentation process. In this configuration, the cooking basket 1 of the present invention is such that the rim or edge 6 of the basket rests on a plurality of support means 11 arranged at the same height on the side wall 3. 10 is arranged.

  As shown in FIG. 4, the support means 11 is at a predetermined height from the bottom 10B of the container 10, and the basket 1 is removed from the bottom 10B and any liquid 12 contained in the container 10. Is still a little away.

  As shown in FIG. 4A, according to an important feature of the present invention, the pressure pan of the present invention has a container 10 which is arranged in a shape in which at least two cooking baskets are stacked inside the container. In order to be able to do so, it has at least two rows of support means 11 arranged at different reference heights. With this arrangement, it is possible to place the first basket 1A in the upper position and the second basket 1B in the lower position, neither basket being immersed in the supply of the liquid 12. This allows the food to be steam-cooked without the food in the basket being mixed as in the prior art using a single basket.

  Furthermore, the circulation of the steam in the closed box of the pressure pan is adjusted by adjusting the density of the plurality of through holes. This makes it possible to perform different cooking without disturbing the lifting operation of the valve lock device.

  As shown in FIG. 5, in a particularly advantageous manner, the method of making the pressure pan food-cooking basket of the present invention is carried out by stamping a metal sheet, for example a stainless steel sheet.

  As shown in FIG. 5, the method includes the following sequential steps:

a) perforating the metal sheet 20;
b) cutting the sheet 20 to obtain a blank 21 in the final shape of the basket, for example a circular shape,
c) stamping the central portion of the blank 21; and
d) trimming the edges to obtain basket 1;

  Of course, it is also possible to begin a method using an already perforated metal sheet without exceeding the scope of the present invention.

  More specifically, if the sheet 20 is perforated in such a way that the plurality of through-holes 4 represent at least 30% of the total area of the sheet, the metal sheet 20 can be, for example, a continuous line or other A series of through-holes 4 of any shape can be advantageously drilled over the entire area.

  The stamping body is carried out in a manner known to those skilled in the art, and the lower limit for making a basket by stamping is related to the concentration or concentration of the through-holes 4 representing at least 30% of the total area of the sheet. .

  As shown in FIG. 5, the deformation of the plurality of through-holes 4 during the initial stamping operation, in particular the elongation different from the others of the top through-holes 4, makes it possible to ensure proper deformation of the sheet, This ensures that stamping is successful.

  The sheet 20 is preferably perforated so that the plurality of through holes represent at least 35%, preferably 35% to 58% of the total area of the sheet.

  As shown, the sheet is perforated over its entire area. During the operation prior to stamping, the sheet is perforated in such a way as to obtain a plurality of through holes that are circular with an average diameter in the range of 3 mm to 5 mm and a pitch in the range of 5 mm to 8 mm; Thereafter, the blank is cut into a circular shape.

  At the end of the initial stamping stage, the edge is trimmed to obtain a substantially radially curved top peripheral edge 6 that is curved outwardly in the basket.

  Thereafter, a circular peripheral ring 7 is placed on the curved peripheral edge 6 and is edge bent to that edge.

  Advantageously, the stamping is carried out in such a way that the joint between the bottom 2 and the side wall 3 of the basket exhibits a certain curvature.

  Thereafter, the handle 8 is placed in the correct position by inserting the end 9A of the handle into the through hole 4.

  Table 1 below steam cooks a variety of vegetables both when cooked in a conventional prior art basket (no purge) and when cooked in a basket of the present invention with a pressure pan purge system. Compare the results of vitamin C storage obtained in the meantime. As an example, for green beans, the purge system is estimated to reduce cooking time by about 35% to 41% and improve vitamin C storage by about 23% to 25%.

  Prior art baskets are comprised of a perforated metal basket with a plurality of apertures of about 3 mm. The plurality of apertures are provided at the bottom of the basket and occupy 20% or less of the total surface area of the basket. The basket of the present invention has a shape similar to that of the basket shown in FIGS. The plurality of apertures 4 are evenly distributed over the entire surface of the basket up to the top edge 6 and represent 30% of the basket area.

  The results clearly show that the cooking time savings obtained with the vegetables in question allow cooking time to be reduced by about 57% to 83%.

  Similarly, vitamin C storage in the vegetables in question was significantly increased as more vitamin C was found to be retained in varying amounts depending on the vegetables. It has been possible to obtain improvements in vitamin retention in the range of 14% to 62%.

  These improved results must be compared to the specific shape of the basket of the present invention, and the size, distribution and density of the through holes 4 help to allow optimal movement of the steam, Promotes excellent heat exchange from the corners of large amounts of vegetables. Thus, it is possible to cook quickly and uniformly, which is necessary to obtain an excellent vitamin reserve.

  The advantageous phenomenon involved can be explained by comparing the graphs shown in FIGS. 6 and 7, which are shown in the basket of the present invention (FIG. 6) and the prior art basket (FIG. 7). This shows the difference in uniformity of food temperature rise in each case.

  These two baskets have the same technical features as the two baskets defined above.

  Temperature levels were measured at different depths in the food with four probes placed in the middle of the basket. From the graph, in the basket of the present invention, the temperature rise of all probes was particularly uniform and rapid over the time interval t1 = 2 minutes 30 seconds to t2 = 5 minutes 30 seconds measured from the start of cooking. You can see that. The final cooking temperature was obtained approximately after 5 minutes 30 seconds of cooking. Since the temperatures measured by all four probes were the same and equal to about 110 ° C., the final cooking temperature was sufficiently equal and uniform in the food, regardless of its position in the basket.

  In contrast, in prior art baskets, the cooking temperature of the food is particularly uneven, and the four temperature curves by all four probes are substantially equal after about 15 minutes of cooking. (Still not perfect).

  During the test, the average cooking pressure was about 1.5 bar. Each pressure pan is fitted with a purge system that allows the steam to be evacuated from the pressure pan enclosure while the pressure increases.

  These graphs also show the rate of temperature increase in the basket of the present invention. Assuming that the average operating pressure reaches about 110 ° C., the entire mass of food has an average operating temperature of about 110 ° C. Conversely, in prior art baskets, an average temperature of 110 ° C. was obtained only after about 14-15 minutes of operation.

  Therefore, these results show that the cooking basket of the present invention is effective in terms of reducing cooking time and preserving vitamins. The basket also offers the advantage of avoiding the creation of localized areas that retain air due to the optimized and uniformly distributed through-holes. Nevertheless, it is important to recognize that saving time and improving vitamin retention is very variable from one vegetable to another, and cooking time is divided between 2.5 and 5.5. And the loss of vitamin C during cooking is reduced by about 1.3 to about 5 times.

Potential Industrial Applications The present invention has potential industrial applications in the design and manufacture of pressure cooker-type household cooking utensils, and also cooking baskets used in connection with the utensils.

FIG. 1 is a perspective view of the cooking basket of the present invention. 2 is a plan view of the same cooking basket as the present invention and the basket shown in FIG. FIG. 3 is a cross-sectional view showing details of the structure of the cooking basket of the present invention. FIG. 4 is a cross-sectional view showing the cooking basket at a high position inside the pressure pan, and FIG. 4A shows the pressure pan of the present invention including two cooking baskets according to the present invention in a stacked arrangement. It is sectional drawing. FIG. 5 illustrates various successive stamping steps that result in the fabrication of the cooking basket of the present invention. FIG. 6 is a diagram showing the uniformity of the temperature rise of the food in the cooking basket of the present invention. FIG. 7 is a graph equivalent to the graph of FIG. 6 and shows the non-uniformity in temperature rise of food contained in a cooking basket of the prior art.

Claims (24)

  A food-cooking basket for pressure cooking in a pressure pan, the basket being formed from a sheet of rigid material defining the bottom (2) and the side wall (3) of the basket (1), said sheet comprising a plurality of sheets In the basket provided with the through-holes (4), the plurality of through-holes (4) are provided to penetrate at least the side wall (3) and represent at least 30% of the total area of the sheet. And a basket.   The plurality of through holes (4) in the side wall (3) start from the bottom of the side wall (3) and are formed substantially uniformly over substantially the entire circumference of the side wall up to a determined height. The basket according to claim 1, wherein: A plurality of through holes (4) is a basket according to claim 1 or claim 2, characterized in that it shows at least 35% of the total area of the sheet.   The basket according to claim 1 or 2, wherein the plurality of through holes (4) represent 35% to 58% of the total area of the sheet.   The plurality of through holes (4) are distributed substantially uniformly over and through the bottom (2) and the side wall (3). Basket described in one.   The basket according to claim 5, wherein the plurality of through holes (4) in the side wall (3) are entirely formed up to a top edge of the side wall (3).   The basket according to claim 1, wherein the plurality of through holes (4) are substantially circular and have a diameter of at least 3 mm.   The basket according to claim 1, wherein the plurality of through holes (4) are substantially circular and have a diameter in the range of 3 mm to 5 mm.   9. Basket according to any one of the preceding claims, characterized in that the joint between the bottom (2) and the side wall (3) has a constant curvature.   The basket according to any one of claims 1 to 9, wherein the basket has a circular shape with a diameter D and a height H = 1 / 3D.   The side wall (3) ends at its apex with a curvilinear edge (6) extending radially outward beyond a constant width around the circumference. A basket according to any one of the above.   12. Basket according to claim 11, characterized in that the curved edge (6) comprises a peripheral ring (7) attached to the edge and bent.   A handle (8) mounted for rotation between a support position and at least one rest position, in which the handle is above the top edge (6) of the basket and at the edge (6). A grip portion substantially following the outer periphery, wherein the handle (8) forms a setback or retracted portion directed inwardly from the rest of the handle (8) 13. A basket according to any one of claims 1 to 12, characterized in that it includes (9) and the grip portion does not rest on the edge (6).   A pressure pan to which the basket according to any one of claims 1 to 13 is attached.   14. A container according to any one of claims 1 to 13 and having a container (10) and a cover, the container (10) being on the wall (3) or on the wall within the container (10). A pressure pan with support means (11) for supporting the placed basket (1), wherein the container (10) stacks at least two cooking baskets (1A, 1B) inside the container (10). Pressure pan, characterized in that it has at least two rows of support means (11) arranged at different heights in order to be able to arrange them together.   A method for producing a food pan for a pressure cooker by stamping a metal sheet, comprising the following sequential steps:
  a) perforating a metal sheet, or starting the method using an already perforated sheet;
  b) cutting the sheet to obtain a blank having the final shape of the basket;
  c) stamping the center of the blank, and
  d) trimming the edges to obtain a basket;
Have
  The method wherein the sheet is perforated such that the plurality of through holes represent at least 30% of the total area of the sheet.   The method of claim 16, wherein the sheet is perforated such that the plurality of through holes represents at least 35% of the total area of the sheet.   The method according to claim 16, wherein the sheet is perforated such that the plurality of through holes represent 35% to 58% of the total area of the sheet.   19. A method according to any one of claims 16 to 18, wherein the sheet is perforated over its entire area.   The sheet is perforated to obtain a plurality of circular through holes having an average diameter in the range of 3 mm to 5 mm and a pitch in the range of 5 mm to 8 mm. Item 20. The method according to any one of Items 19.   The method according to any one of claims 16 to 20, wherein the blank is cut out in a circular shape.   22. A method according to any one of claims 16 to 21 wherein the edges are trimmed to obtain a substantially outwardly curved top peripheral edge in the basket.   23. A method according to claim 21 or claim 22, wherein a circular peripheral ring is disposed on the curved peripheral edge and is edge-bent to the edge.   24. A method as claimed in any one of claims 16 to 23, wherein the stamping is performed such that the joint between the bottom and the side wall of the basket exhibits a constant curvature.

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